Recent analysis of data from the National Household Survey on Drug Abuse indicates that the estimated number of people age 50 or older in need of substance abuse treatment is expected to increase from 1.7 million in 2000/2001 to 4.4 million in 2020. Depressive disorders among opiate abusers have detrimental effects on their well-being and ability to refrain from illegal drug use. This Mentored Clinical Scientist Development (K-08) Award seeks to promote the Candidate's long-term goal to become an independent clinical investigator researching effective psychosocial treatments for late-life depression among older adults with drug dependence problems. The training and research activities described in this application will take place in the cross-disciplinary environment of the School of Social Work, the Advanced Center for Interventions and Services Research for Late-life Mood Disorders (Reynolds, PI), and the Drug Abuse Vulnerability: Mechanisms and Manifestations Center (Cornelius, Director of the Clinical Core) at the University of Pittsburgh. Training will enable the Candidate to become proficient in the adaptation, testing, and delivery of an intervention for older adults with co-occurring substance abuse and depression disorders and to develop the knowledge necessary to integrate an effective treatment model into the standard of care offered by substance abuse treatment facilities. The Candidate's pilot work with older methadone clients identified Problem Solving Therapy (PST) as the most appropriate therapeutic intervention for this population. PST is an empirically tested treatment approach for older adults for the treatment of depression. The research plan will be implemented at a methadone clinic that serves a diverse clientele-a third are over the age of 50, nearly half (44%) of whom are African-American. Phase 1 of this research plan will be a PST certification study to obtain the necessary qualifications in PST for all counselors involved in the project. Phase 2 of the research plan will include a randomized clinical trial comparing 60 participants receiving the PST intervention to 60 participants receiving treatment as usual (TAU). On the basis of the data, Phase 3 will be devoted to data analysis, manuscript development, and the writing and submission of an R-01. Understanding the relationship between substance abuse and psychiatric disorders is critical to providing appropriate services to a growing and aging addicted population in the United States.